DocView mode is a major mode for viewing DVI, PostScript (PS), PDF,
OpenDocument, Microsoft Office, EPUB, CBZ, FB2, XPS and OXPS
documents. It provides features such as slicing, zooming, and
searching inside documents. It works by converting the document to a
set of images using the gs (GhostScript) or
pdfdraw/mutool draw (MuPDF) commands and other
external tools, and then displays those converted images.
When you visit a document file that can be displayed with DocView
mode, Emacs automatically uses that mode 28. As an exception, when you visit a PostScript file, Emacs
switches to PS mode, a major mode for editing PostScript files as
text; however, it also enables DocView minor mode, so you can type
C-c C-c to view the document with DocView. In either DocView
mode or DocView minor mode, repeating C-c C-c
(doc-view-toggle-display) toggles between DocView and the
underlying file contents.
When you visit a file which would normally be handled by DocView mode
but some requirement is not met (e.g., you operate in a terminal frame
or Emacs has no PNG support), Emacs asks if you want to view the
document’s contents as plain text. If you answer yes, Emacs turns on
Text mode in the buffer and activates DocView minor mode. Thus, by
typing C-c C-c, you switch to this fallback mode. With another
C-c C-c you return to DocView mode. The plain text contents can
also be displayed in a separate buffer named like the original document
buffer with suffix /text by typing C-c C-t
(doc-view-open-text) from within DocView mode.
You can explicitly enable DocView mode with the command M-x doc-view-mode. You can toggle DocView minor mode with M-x doc-view-minor-mode.
When DocView mode starts, it displays a welcome screen and begins formatting the file, page by page. It displays the first page once that has been formatted.
To kill the DocView buffer, type k
(doc-view-kill-proc-and-buffer). To bury it, type q
(quit-window).
The needed external tools for the document type must be available, and Emacs must be running in a graphical frame and have PNG image support. If these requirements is not fulfilled, Emacs falls back to another major mode.